The present invention relates to a ceiling ventilation device and, more particularly, to a ceiling fan unit and a mounting arrangement therefor.
Rising electrical power costs and the resulting increased costs of operating residential air conditioning units have increased the interest in alternative methods of cooling a home. One such method is to provide a ceiling fan unit which draws air into the home through windows and doors and exhausts air from the home interior into the attic, and from the attic to the outside through properly sized vents. Typically, the fan unit is mounted in a central location, suc as a hallway ceiling, so that the cooling effect of the fan unit is distributed evenly through the house. During cooler times of the day and at night, the fan is turned on, drawing the cool outside air into the home. In the morning, the doors, windows, drapes, and shades may be closed to hold in the cool air.
While such ventilation devices, commonly termed whole house ventilators or attic fans, when used either alone or in conjunction with an air conditioning system, can reduce substantially the energy costs associated with cooling a home, installation of such prior art ventilation devices is relatively difficult and expensive, especially in existing homes. To install a prior art ventilation device, a central location is selected for the fan unit and a hole is cut through the plaster or dry wall ceiling. Homes are typically constructed utilizing 2".times.6" ceiling joists spaced on 16" centers or triangular roof trusses of 2".times.4" or 2".times.6" lumber spaced on 24" centers. The lower horizontal portions of the trusses are termed runners or joists and perform essentially the same ceiling support function as the joists in a joist construction home. Hereafter, the parallel horizontal wooden support members directly above the dry wall or plaster ceiling will be referred to as "joists", with it being understood that this term applies to such members used in both joist and truss construction.
Depending upon the size of the fan unit to be installed, it may be necessary to cut one of the joists to provide an opening in the ceiling sufficient in size to receive the fan unit. If a 22".times.22" fan unit is to be installed in the ceiling of a home having joists on 24" centers, it is not necessary to cut any of the joists. If, on the other hand, a 22".times.22" fan unit is to be installed in the ceiling of a home having joists on 16" centers or a 30".times.30" fan unit is to be installed in the ceiling of a home having joists on 16" or 24" centers, one of the joists must be cut.
After cutting an opening in the dry wall or plaster of appropriate size to receive a shutter assembly or intake grill, and cutting a ceiling joists, if necessary, the ceiling opening is then framed in with lumber of the same size as the joists to provide a frame in which the shutter assembly is mounted. An additional frame is constructed for mounting the fan unit above the shutter assembly. Wiring must then be provided to power the electric motor of the fan unit and, typically, wires must be fished down into a wall close to the fan unit and connected to wall mounted control switches. Although wiring a prior art ceiling fan unit is not as difficult when the unit is installed at the time that the home is under construction, nevertheless, a support frame must be constructed to mount the shutter assembly and fan unit in the ceiling.
An additional problem exists with respect to prior art ceiling fan units. Typically, the attic of a home is insulated with fiber glass or cellulose insulation, with the insulating material being placed between the joists on top of the dry wall or plaster ceiling. In view of the fact that the fan unit exhausts air into the attic, it is not possible to cover the fan unit with such an insulation. As a consequence, the homeowner must manually cover the fan unit with insulation material over the shutter assembly or in the attic each fall and remove the insulation material each spring prior to use of the fan. This is inconvenient.
Accordingly, there is a need for a ceiling ventilation device which is simple in construction, which is easily mounted in a ceiling opening, and in which thermal insulation and sealing are provided to prevent heat loss and drafts through the device during periods in which the device is not in operation.